1. Field of the Invention
The present invention relates to a method and a system for localization.
2. Description of Related Art
Along with the popularity of wireless mobile equipments day by day, more and more users accomplish the daily life activities through mobile devices. Accordingly, various wireless technologies are drastically boosted, wherein WiFi (wireless fidelity) is counted as the most popular one. With the full development of various wireless technologies, many relevant equipment manufacturers have emphasized on the value-added applications (VAAs) of the wireless environments, one of which is to provide a position sensing service regarding position information. A user can obtain various information and services at the surrounding areas by means of the position sensing service, such as searching for ‘the nearest restaurants’, ‘the closest public traffic means’, and so on. In response to the queries from users, the service provider would provide users with the most suitable information in this regard according to their positions.
In the expectable future, the position sensing service is a valued investment for the telecom network service companies, wherein the maturity of the positioning system is the key; namely, how to provide a stable and low cost localization equipment gradually becomes a highly concerned issue. In an outdoor environment, the most used position sensing equipment is a global positioning system (GPS), through which the correct information of a user's position can be conveniently obtained. Here, the accuracy of the information within a range from a couple of meters to tens of meters is determined upon the hardware equipment.
On the other hand, in an indoor environment, no appropriate positioning system used by public is available now. The reason in the regard firstly rests in an inaccuracy arisen from the conventional positioning system, because an indoor space is relatively narrow in comparison with an outdoor environment. The dense indoor environment requires a much higher localization accuracy of the indoor positioning system. Secondly, a feasible positioning system targeting indoor environments requires additional expensive hardware cost. For example, a user in a specific indoor environment needs to be equipped with an additional hardware device, bringing about inconvenience and extra costs. Therefore, there is no effective solution for indoor localization yet. However, there are still some representative indoor localization plans including, for example, ‘Active Bat plan’ focusing on the position precision or ‘RADAR plan’ otherwise in consideration of the hardware cost.
The ‘RADAR plan’ introduces a positioning system based on a pattern-matching algorithm. The system has two phases: training and positioning. In the first phase, a lot of training positions with given coordination are disposed in a building in advance. Then, the signal intensities of the surrounding access points are received and collected at the training positions, so that once a sufficient number of the characteristic samples are collected, all the collected characteristic samples are stored in a database to thereby create a positioning module required by localization. In the second phase, users can identify their positions by inquiring the contents of the positioning module according to the signal intensity information collected in a real-time manner. After comparing the information with use of the positioning module, the most-likely position is stored into a position sensing system, which serves as a position sensing service to be provided to internet application programs.